Toners and/or toner mixtures

ABSTRACT

A toner or a mixture of toners, comprises a pyrogenically synthesized alumina-silica mixed oxide as a component in combination with other components necessary to complete a toner formulation. The surface of the mixed alumina-silica oxide material.

This application is a Continuation of application Ser. No. 09/461,752Filed on Dec. 16, 1999, now U.S. Pat. No. 6,197,469.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to toners and/or toner mixtures.

2. Discussion of the Background

U.S. Pat. No. 5,424,258 discloses powdered silicon-aluminum mixed oxidesof amorphous structure, synthesized by flame hydrolysis. The oxidecompositions contain 65 to 72.1 wt. % Al₂O₃ and 27.9 to 35 wt. % SiO₂and have a BET surface ranging from 20 to 200 m²/g.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a toner and/or tonermixture which contains pyrogenically synthesized alumina-silica mixedoxide which improves the properties of the toner and/or toner mixture.

Briefly, this object and other objects of the present invention ashereinafter will become more readily apparent can be attained by a tonerand/or toner mixture which contains a pyrogenically synthesizedsilica-alumina mixed oxide as a component in addition to othercomponents which complete a toner formulation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The discovery of the present invention is that the presence of apyrogenically synthesized silica-alumina mixed oxide as an additive to atoner imparts improved properties to the toner. The amount of thepyrogenically synthesized silica-alumina incorporated in the tonernormally ranges from 0.1 to 5.0% by weight based on the weight of toner.Other toner components include a pigment such as Fe₂O₃, a binder such aspolyester resin and a charge controlling agent in the amounts theseingredients are normally used to prepare a toner.

The pyrogenically synthesized alumina-silica mixed oxide of theinvention is per se known and can be prepared as described in U.S. Pat.No. 5,424,258 which is hereby incorporated by reference into theapplication.

In an embodiment of the invention, the Al₂O₃/SiO₂ mixed oxide may have aratio of Al₂O₃ to SiO₂ comprising 65±5 wt. %Al₂O₃ and 35±5 wt. % SiO₂.

In another embodiment of the invention, the pyrogenically synthesizedAl₂O₃/SiO₂ mixed oxide can be surface-modified. The surface modificationof the mixed alumina-silica oxide material can be achieved by thetechnique described in European Patent EP 0 722 922, hereby incorporatedby reference. Suitable surface treatment compounds include:

(a) Organosilanes of the type (RO)₃Si(C_(n)H_(2n+1))

R=alkyl, such as e.g., methyl-, ethyl-, n-propyl-, i-propyl-, butyl—

n=1-20

(b) Organosilanes of the type R′_(x)(RO)_(y)Si(C_(n)H₂₊₁)

R=alkyl, such as e.g. methyl-, ethyl-, n-propyl-, i-propyl-, butyl—

R′=alkyl such as e.g. methyl-, ethyl-, n-propyl-, i-propyl-, butyl—

n=1 -20

x+y=3

x=1,2

y=1,2

(c) Organosilanes of the type (RO)₃Si(CH₂)_(m)—R′

R=alkyl, such as methyl-, ethyl-, propyl—

m=0, 1 -20

R′=methyl-, aryl (e.g., —C₆H₅, substituted phenyl groups)

—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF2

—NH2, —N₃, —SCN, —CH═CH₂,

—OOC(CH₃)C═CH₂

—OCH₂—CH(O)CH₂

—S_(x)—(CH₂)₃Si(OR)₃

(d) Organosilanes of the type (R″)_(x)(RO_(y)Si(CH₂)_(m)—R′

R′=methyl-, aryl (e.g. —C₆H₅, substituted phenyl groups)

—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂

—NH₂—N₃, —SCN, —CH═CH₂,

—OOC(CH₃)C═CH₂—

—OCH₂—CH(O)CH₂

—NH—COO—CH₃, —NH—COO—CH₂—CH₃, —NH—(CH₂)₃Si(OR)₃

—S_(x)—(CH₂)₃Si(OR)₃

(e) Halogenorganosilanes of the type X₃Si(C_(n)H_(2n+1))

X=Cl, Br

n=1-20

(f) Halogenorganosilanes of the type X₂(R′)Si(C_(n)H₂₊₁)

X=Cl, Br

R′=alkyl, such as e.g. methyl-, ethyl-, n-propyl-, i-propyl-, butyl—

n=1-20

(g) Halogenorganosilanes of the type X(R′)₂Si(C_(n)H_(2n+1))

X=Cl, Br

R′=alkyl, such as e.g. methyl-, ethyl-, n-propyl-, i-propyl-, butyl—

n=1-20

(h) Halogenorganosilanes of the type X₃Si(CH₂)_(m)—R′

X=Cl, Br

m=0, 1-20

R′=methyl-, aryl (e.g. —C₆H₅, substituted phenyl groups)

—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂

—NH2, —N₃, —SCN, —CH═CH₂,

—OOC(CH₃)C═CH₂

—OCH₂—CH(O)CH₂

—S_(x)—(CH₂)₃Si(OR)₃

(i) Halogenorganosilanes of the type (R)X₂Si(CH₂)_(m)—R′

X=Cl, Br

R=alkyl, such as methyl-, ethyl-, propyl—

m=0, 1-20

R′=methyl-, aryl (e.g. —C₆H₅, substituted phenyl groups)

—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂

—NH₂, —N₃, —SCN, —CH═CH₂,

—OOC(CH₃)C═CH₂

—OCH₂—CH(O)CH₂

 in which R can be =methyl-, ethyl-, propyl-, butyl

—S_(x)—(CH₂)₃Si(OR)₃ in which R can be =methyl-, ethyl-, propyl-, butyl—

(j) Halogenorganosilanes of the type (R)₂X Si(CH₂)_(m)—R′

X=Cl, Br

R=alkyl

m=0, 1-20

R′=methyl-, aryl (e.g. —C₆H₅, substituted phenyl groups)

—C₄F₉, —OCF₂—CHF—CF₃, —C₆F₁₃, —O—CF₂—CHF₂

—NH₂, —N₃, —SCN, —CH═CH₂,

—OOC(CH₃)C═CH₂

—OCH₂—CH(O)CH₂

—S_(x—(CH) ₂)₃Si(OR)₃

(1) A preferred silazane in hexamethyldisilazane (HMDS). Cyclicpolysiloxanes of the type D 3, D 4, D 5 in which D 3, D 4 and D 5signify cyclic polysiloxanes with 3, 4 or 5 units of the type—O—Si(CH₃)₂—, e.g., octamethylcyclotetrasiloxane=D 4

(m) polysiloxanes or silicone oils of the type

m=0, 1,2,3. . .∞

n=0, 1,2,3. . .∞

u=0, 1,2,3. . .∞

Y=CH₃, H, C_(n)H_(2n+1) n=1-20

Y=Si(CH₃)₃,Si(CH₃)₂H

Si(CH₃)₂OH, Si(CH₃)₂(OCH₃)

Si(CH₃)₂(CnH_(2n+1))n=1-20

R=alkyl such as C_(n)H_(2n+1) in which n=1 to 20, aryl such as phenyl-and substituted phenyl groups (CH₂)n—NH₂, H

R′=alkyl such as C_(n)H_(2n+1) in which n=1 to 20, aryl such as phenyl-and substituted phenyl groups (CH₂)n—NH₂, H

R″=alkyl such as C_(n)H_(2n+1) in which n=1 to 20, aryl such as phenyl-and substituted phenyl groups (CH₂)n—NH₂, H

R′″=alkyl such as C_(n)H_(2n+1) in which n=1 to 20, aryl such as phenyl-and substituted phenyl groups (CH₂)n—NH₂, H

The pyrogenically produced alumina-silica mixed oxide is placed in asuitable mixing container. The mixed oxides are sprayed under intensivemixing optionally with water at first and then with thesurface-modifying reagent or a mixture of several surface-modifyingreagents. The material is mixed again for 15 to 30 minutes andsubsequently tempered at a temperature of 100 to 400° C. for a period of1 to 6 hours.

The water used can be acidified with an acid, e.g., hydrochloric acid,having a pH of 7 to 1. The surface-modifying reagent used can bedissolved in a suitable solvent such as, e.g., ethanol. The mixingand/or tempering can be carried out in an atmosphere of a protective gassuch as, for example, nitrogen.

As a result of the incorporation of the pyrogenically synthesized, mixedalumina-silica oxide material of the invention, or the oxide materialwhich is surface modified as mentioned above, into a toner formulationand/or toner formulation mixtures, the toner product of the inventionhas the following advantages:

(i) Better flowability of the toner powder;

(ii) More stable charging behavior of the toner as characterized byfaster chargeability, a higher charge capacity and permitting constantcharging over time.

Having now generally described this invention, a further understandingcan be obtained by reference to certain specific examples which areprovided herein for purposes of illustration only and are not intendedto be limiting unless otherwise specified.

EXAMPLES Example 1

A Al₂O₃/SiO₂ mixed oxide is synthesized as follows:

In accordance with the burner arrangement described in Example 1 of U.S.Pat. No. 5,424,258, 1.4 m³/h (NTP) of nascent hydrogen, or hydrogen ofreaction, is mixed together with 5.5 m³/h (NTP) of air and 1.30 kg/h ofpreviously evaporated SiCl₄. Into this mixture, which has a temperatureof about 200° C., there is additionally injected 2.34 kg/h of gaseousAlCl₃, which had been evaporated beforehand at about 300° C. Theresulting mixture is burned in a flame tube, into which 12 m³/h (NTP) ofair is additionally injected.

After passing through the flame tube, the resulting powder is separatedin a filter or cyclone from the gases, which contain hydrochloric acid.The adhering residues of hydrochloric acid are separated from thecollected mixed oxide by treatment at elevated temperature.

The mixed oxide is characterized by the following analytical data:

Specific BET surface 74 m²/g, a 4% dispersion in water having a pH of4.49, an apparent density of 46 g/l, a tamped density of 56 g/l. Thecomposition of the powder is 65 wt. % Al₂O₃ and 35 wt. % SiO₂.

Example 2

The surface of a mixed alumina-silica oxide,is modified as described inEuropean Patent Application A 0 722 992:

A 600 g amount of a mixed alumina-silica oxide material is placed in aplow-type mixer and, while being mixed, is sprayed first with 30 g ofdistilled H₂O and then with 90 g of HMDS (hexamethyldisilazane).Thereafter mixing is continued for a further 15 minutes and finally thereaction mixture is dried for 3 hours at 140° C. in a drying cabinet.

The physicochemical data of the product are as follows:

Experiment 1 Experiment 2 Tamped density [g/l] 96 88 pH 7.4 7.8 Ccontent [% m²/g] 0.7 0.9 Surface [m²/g 62 65 Drying loss [%] 0.7 0.3Ignition loss [%] 1.4 2.1

Example 3

A 1.8 kg amount of the Al₂O₃/SiO₂ mixed oxide described above is placedin a mixer and, while being mixed, is sprayed with 0.27 kg of siliconeoil. Thereafter, the surface treated mixed alumina-silica oxide is mixedfor an additional 15 minutes and finally subjected to a heat treatmentat 300° C. for 2 hours under N₂ atmosphere (fluidized bed).

Physicochemical data: Tamped density Lg/11 106 BET surface [m²/g]: 57pH: 4.2 C content [%]: 1.3 Drying loss [%]: 0.2 Ignition loss [%]: 1.6

The disclosure of German priority Application No. 198 57 912.8 filedDec. 16, 1998 is hereby incorporated by reference into the presentapplication.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is,therefore, to be understood that within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallydescribed herein.

What is claimed as new and is intended to be secured by Letters Patentis:
 1. A toner or a mixture of toners, comprising: a pyrogenicallysynthesized alumina-silica mixed oxide as a component in combinationwith other components necessary to complete a toner formulation; whereinthe amount of the pyrogenically synthesized alumina-silica mixed oxideincorporated into the toner ranges from 0.1 to 5.0% by weight based onthe weight of toner.
 2. The toner or toner mixture according to claim 1,wherein the pyrogenically synthesized alumina-silica mixed oxide issurface-modified using a surface-modifying agent.
 3. The toner or tonermixture according to claim 2, wherein the surface-modifying agent is anorganosilane, a halogenorganosilane, a silazane, a polysiloxane or asilicone oil.
 4. The toner or toner mixture according to claim 3,wherein the surface of the mixed alumina-silica is modified by treatmentwith hexamethyldisilazane.
 5. The toner or toner mixture according toclaim 3, wherein the surface of the mixed alumina-silica is modified bytreatment with silicone oil.
 6. The toner or toner mixture according toclaim 3, wherein the surface of the mixed alumina-silica is modified bytreatment with octamethylcyclotetrasiloxane.
 7. A method of preparing atoner or a toner mixture, comprising: mixing a pyrogenically synthesizedalumina-silica mixed oxide with the other components necessary tocomplete a toner composition; wherein the amount of the pyrogenicallysynthesized alumina-silica mixed oxide incorporated into the tonerranges from 0.1 to 5.0% by weight based on the weight of toner.
 8. Themethod according to claim 7, wherein the pyrogenically synthesizedalumina-silica mixed oxide is surface treated.
 9. A toner or a mixtureof toners, comprising: a pyrogenically synthesized alumina-silica mixedoxide obtained by a method comprising: mixing nascent hydrogen with airand SiCl₄ gas; adding gaseous AlCl₃, thereby obtaining a gas mixture;burning said gas mixture in a flame tube into which additional air hasbeen injected, thereby obtaining a powder; separating said powder fromsaid gas mixture; heating said powder, thereby reducing an amount ofadhered HCl.
 10. The toner or a mixture of toners of claim 9, whereinthe pyrogenically synthesized alumina-silica mixed oxide is surfacetreated.
 11. A method of preparing a toner or a toner mixture,comprising: mixing a pyrogenically synthesized alumina-silica mixedoxide with other components necessary to complete a toner composition;wherein said pyrogenically synthesized alumina-silica mixed oxide isobtained by a method comprising mixing nascent hydrogen with air andSiCl₄ gas; adding gaseous AlCl₃, thereby obtaining a gas mixture;burning said gas mixture in a flame tube into which additional air hasbeen injected, thereby obtaining a powder; separating said powder fromsaid gas mixture; heating said powder, thereby reducing an amount ofadhered HCl.
 12. The method according to claim 11, wherein thepyrogenically synthesized alumina-silica mixed oxide is surface treated.